542 SPORADIC DISEASES. 



conducts the action of the cerebellum upon the body is composed 

 of the restiform bodies and small posterior pyramids in the 

 anterior part, and of the superior columns of the cord in the 

 posterior part of its course. 



Section of the inferior columns, if made immediately behind 

 the medulla oblongata, is not followed by any very obvious loss 

 of paralysis or loss of sensation, unless the cut be extended 

 to the lateral column, when loss of motion is the result, as if 

 the columns were divided behind this point. It is therefore 

 apparent that in the anterior part of their course the inferior 

 columns have not an intimate connection with the correspond- 

 ing roots of the spinal nerves. Posterior to this, however, they 

 have a close connection with the inferior roots of the spinal 

 nerves and with voluntary motion. They have also some con- 

 nection with sensibility, as a certain degree of numbness is 

 produced by injuries which give rise to loss of motion. 



Inferior pyramids. — Section of one of these pyramids in any 

 part of its course is followed by immediate loss of voluntary 

 movements in the muscles below the cut on the opposite side of 

 the body ; but sensation is not affected in any appreciable manner. 

 Lateral columns. — In the cervical region, for a short distance 

 behind the point at which the inferior pyramids of the medulla 

 oblongata decussate, the lateral columns of the spinal cord are 

 directly concerned in conveying the stimulus of the will to the 

 muscles on the same side of the body, for when they are cut 

 across paralysis of the muscles of the same side occurs. 



In the lower part of the neck, and regions posterior to this, 

 the same results are not seen ; for when they are divided in 

 these regions, some trifling paralysis ensues, with some degree 

 of anesthesia and loss of co-ordination. 



Olivary hodies. — When one of these is divided, a persistent 

 spasm of many muscles of tlie same side is the result. 



Giry suhstance of the cord. — Dr. Brown Sequard says that the 

 grey substance of the cord is an important conductor of sensory 

 and motor impressions. Paralysis, without loss of sensation on 

 the same side of the body, are the results of cutting across one 

 lateral half of the grey substance of the cord. Anaesthesia on 

 both sides of the body, paralysis of neither side, are the strange 

 results of making a longitudinal section midway between th^ 

 two lateral halves. 



